Patent GB-586827-A (GB)
Title: Improvements in or relating to a photographic shutter
IPC: G03B9/20
Filed: 1944-12-22
Abstract: 586,827. Photographic shutters. KODAK, Ltd. Dec. 22, 1944, No. 25762. Convention date, Feb. 25. [Class 98 (i)] In a photographic shutter in which a master member operates the shutter blades, one of a pair of interconnected and oppositely movable rings is actuated by a cam carried by the master member to open and close the shutter blades, the cam striking during the release movement, a cam follower in the form of a pivoted lever connected to one of the blade rings, the lever being carried on an adjustable support to vary the point of impact and thus the speed of operation of the shutter. The exposure aperture of the camera is closed by a plurality of shutter leaves 4, each leaf comprising two similar ends 5 and being pivoted at 12 to the blade ring 7 and connected by a pin 13 and slot 14 to another blade ring 6. The rings 6, 7 are linked by a rocker arm 8. The blade ring 6 has an arm 15 carrying a pin 15<1> which engages a slot 16 in one end of a pivoted bell crank lever 18, the other arm of the lever having a curved end 21 acting as a cam follower. The master member comprises a ring 22 turning in a groove 23 in the mechanism plate and constrained by a spring 37, secured respectively to the ring, 22, and the casing. The setting lever 25 extends through a slot in the casing and the ring 22 carries a cam 27 comprising two inclined surfaces 28, 29 connected by a surface 30, which is concentric with rings 6, 7. The master member is retained in its set position by means of a lug 32 on the ring 22, engaging a latch element 33, carried by the spring-pressed trigger 34. During tensioning of the master member spring, a wire spring 84 anchored to the ring 22 acts on a pin 86 on the blade ring 7 to turn it in a clockwise direction and thereby to move the bell crank lever 18 to the position shown in Fig. 1. If then the trigger 34 is depressed, the cam 27 moves anticlockwise and the surface 28 engages the end 21 of the lever and causes the shutter blades to move to the open position, in which they remain whilst the concentric part 30 of the cam passes beneath the end 21. When the end 29 of the cam is engaged the lever is moved further and closes the shutter blades. The stud 19 carrying the lever 18 is engaged by a cam surface 40 on a plate 41, which is connected to a speed-adjusting ring on the outside of the shutter casing. The stud is supported on a pivoted link 44 which is turned by a spring 52 so that the stud is in engagement with the plate. A cam 60, adjustable by means of a tool in a slot 61, determines the limit of movement of the plate 44. When a higher shutter speed is required, the ring 43 is turned to move the stud 19 so that the cam follower 21 is not engaged by the cam surface 28 during the running down of the master member, the inclined surface 29, striking the follower 21 to open and close the shutter blades. The exposure aperture is closed during the setting of the shutter by supplementary shutter leaves 70, 71 which are swung across when a latch member 80 on the master member engages a pin 74 constrained to move in a slot and open and close the supplementary leaves, as described in Specifications 580,074 and 582,774.